Go to Website Homepage Webmaster: Phil@scmec.us
Want to know more about the Club?

Back to last page

Was There A No.12 Erector in 1929?

Building A Model Seen Only in A Catalog

By Bob Galler

(You can view enlarged images by clicking on the pictures. Use your browser's 'back' button to get back to this page)

Some time ago we heard Anton say that Erector fans wanted a more representative newsletter on the Erector side, and in this regard, could we please prepare articles about Erector models that had been constructed. After a layoff from Erector due to several distractions, not the least of which was moving to a new house, I decided to give the old Erector scene new effort, similar to when I was new to the hobby.

After building some complicated Meccano models over the last several years, it was an easy task to warm to Erector again, poring over the old manuals and parts supplies. The first challenge was to build something I had never built before, or had not seen built before. The second challenge would be clarifying one of the old large models for others perhaps using computer graphics and instructions. Third, the effort had to be fun. As an added incentive during the move from Santa Fe to Rio Rancho I became intimately familiar with my parts inventory (especially their gravitational properties!) on the Erector side again, and this allowed scope for appreciating the older Erector parts range.

Some of us remember when no one we knew, not even Clyde Suttle, had seen or obtained the large 1931-1933 Erector No.10 set. There were some rough pictures floating around of such a set that was reportedly lost in a Texas storm. Remember? The old pros speculated on its actual existence and what really went in it, what the inside lid picture would be based on an old Gilbert catalog; and, of course, how much it weighed. Then a few of those sets appeared in various condition, and most agree that the owners are lucky indeed!

Now the old pros are certain for sure that there was a set that never really existed because neither they nor anyone they know owns one or has seen one. That would be the 1929 No.12 set, many models of which appear in the catalog entitled No.10 & 12-Deluxe Master Engineer's Set-Builds All Erector Feature Models. The manual exists as a certainty. This era was before the Hudson was produced, so the section for Set 12 contains only more, much more, of the existing basic Erector parts from which to build. Although all of the No.12 models were large and massive, they evoked nothing of further interest or detail beyond models built with the No.10 set.

Did the set exist, and in what form? Was it a factory special order for some well-to-do young man? Would it arrive in separate parts containers? Certainly, no one wanted to lug around 200 or so pounds of plates that would have been required in one container. Time may or may not tell.

Anyway, to make the issue more interesting, I decided to build the No.12 Giant Walking Beam Engine-just to show that it could be done. I feel certain it was constructed before in the Erector model room of 1929 (try drawing up such a model without having it in front of you.)

To enhance the building instructions, of which Gilbert supplied none, the manual page was scanned and made into a bitmap. The bitmap was over two megs and had to be zipped to fit on one disc. The scanned image was imported into Powerpoint 4.0 and was then available to add part numbers and arrows. Before we get into the building instructions and notes, it must be stated that the manual plan was followed as closely as possible. If you have seen works by M.C.Escher you will be familiar with following the manual plan. For example, one end of the base is clearly shown as being the width of three S plates; the other end, as one continuous plate. The correct width was found to be that of two S plates. In another case, the rear end view (not the view scanned) would indicate that the right inside bearing support arm of DV girders runs both inside and outside the flywheel at the same time. Be that as it may, the model closely matches the plan.

In some places, I had to supplement the required Erector parts with their Meccano counterparts because they were available and the quantity of Erector parts required was beyond my resources. In other instances, the axle sizes and/or lengths were never made in Erector, such as 11" long " or 5/16" axles, etc. and these were made from drill rod blanks available at your local industrial tool supply house.

The finished model is handsome in red, black and nickel. The beam arm was counterbalanced internally for smoother operation, the model does operate and has been run briefly just to show that it will, but only briefly so as to spare the P56G motor. Photos are available upon request to assist if you would like to build the model. What could be better than building your own model, first designed and perhaps never built again since 1929? For the set collector, the model represents an abstract need of the builder, not related at all to the value of the collected set sitting there in its box, parts all neatly arranged and inventoried. Quick! Obtain the set, take a picture of it and tell your jealous fellow collectors then make sure you hide it away in your attic or hobby room. Consider it as part of your portfolio. After all, what's more important than one's set inventory?

For me, the fun comes from any part of the hobby which gives relaxation and recreation, because in our little world of collecting and building, we can do whatever we want-something that life outside our little Erector (or Meccano) world rarely offers. My recommendation: Break out some of those sets and parts and find the enjoyment of building a model or two; afterwards you can still carefully repack the sets, none the worse for wear. Of course, if an item is truly like new in the box, never touched, then by all means use other inventory. Enjoy!

All references to left and right, front and back, are based on the isometric drawing with numbered parts below. (Click on the picture below to download the full sized version and see all the details)

The Base

The base is made in the following dimensions: Width is 20"; Length 50". Each end is composed of four S plates overlapped one row of holes both vertically and horizontally. The front and rear sides of the base require six each DQ plates and two S plates.

The orientation from left to right will be: Two DQ's, two DQ's, two S's and two further DQ's. The S's overlap two holes on both ends with adjoining DQ's.

All other overlapping is one hole. The top of the base consists, from left to right, of twelve S plates (6 rows x 2) overlapped one hole in both directions, being attached to the underside of the side plate flanges..

The farthest plates to the right will have the flange down on the right end. Put in enough bolts to make the assembly rigid, some will be taken out later to insert the railing sections.

Next, in the same orientation, will be four more S plates, leaving 19 holes between these plates and the previous 12 plates, these four being overlapped one hole in each direction. You will become proficient with the base construction as you build.

Finally, running perpendicular to these four plates will be six more S plates joined so that the center section of plates has three rows of holes exposed. These plates are centered lengthwise looking at the right end of the base. This will create a flywheel opening of 12 holes between the base front and rear and either side of this center channel assembly.

The frame as is was too flexible, and DP angle girders were overlapped and used for lateral support at two places at the lower flange of the DQ side plates (from the inside). To keep the plates and bolts from scraping the work table, and for support and leveling, six P7 pulleys with CL small rubber tires were screwed to the base from below, the locations not being critical.

The guard rails, composed of a combination of five- and seven-inch axles, connected by AB couplings (Meccano P.N.63 Couplings could be substituted) can be added after final assembly.


Both flywheels are made exactly the same. They are in the classic No.12 set design. Five EA or EW flat flexible plates are formed into a wheel, one hole overlapping at each joint. Use four bolts at each joint, one at each side and two spaced one hole apart from the center hole. This allows the drive string to ride directly in the wheel center and conforms with the bolt pattern required for fastening the K 11-hole strip brackets.

The K brackets, eight per wheel, are spaced 15 holes apart. At least one will fall on a plate joint. Each spoke is made from two overlapped B girders, and 32 spokes should be made. The overlap should form a spoke girder 7" from end hole to end hole.

Each spoke is secured to one end at the K brackets and the other end at the outer holes in the AZ Bull Ring Plates (plates to the outside of the spokes.) BAX Bull Wheel Centers are fastened to the plates with four bolts, do not over-tighten.

Each wheel should be secured to a shaft, the centers locked down on the shaft so that the natural width of the plate to plate location is increased two inches beyond the free width. Each wheel should now be trued and screws securely tighten-ed. Remove the shafts from the wheels.

Flywheel Supports and Bearings

Four flywheel supports are made identically. Two DV girders are over-lapped one hole, making a side plate and fastened to two further DV's making the other side plate. M small double angles are use at one end and the middle as spacer supports between the DV side plates.

Two of these assemblies are contained at their ends between two BB Segment Plates and secured by bolts through the third hole up from the BB sides. One BAX as a shaft bearing is centered in the BB and fastened with four bolts, do not tighten at this time.

Two of the support assemblies are mounted to the outside of the frame (one front, one rear) as follows: The right hand support is bolted to the base side plates, by a _" bolt inserted through the lowest corner hole in the support, through the DV's and into the second hole from the base bottom flange and 12 holes from the right corner of the base.

The left leg of the support is fastened the same way, separated from the right-hand support hole by 22 holes. For further support, _" bolts fasten the DV's at the top hole of the base (use washers under the heads since the hole is a small triangle.) These two holes are 17 and 28 holes respectively from the base right corner. Two of the support assemblies are mounted to the inside of the base as follows: Inside the base, two compound angle girders are made from overlapped DP girders which are in length equal to the base width.

The girders are fastened to the lower base in the location of the lowest outer holes of the already attached supports (i.e. 12 holes and 36 holes from the right end of the base respectively).

Each inside DV support will have two O Pawls fastened to the lowest side hole and the Pawls are then bolted to the angle girders just installed.

The upper portion of the supports are bolted to the flange of the S plates at the same hole spacing as the outer support frames. Do not tighten anything yet.

Now take a straight length of " shaft about 30" long and carefully insert it through all four BAX bearings of the supports. Make sure all the support arms are vertical by tightening the screws which fasten them to the side plates.

While you insure easy turning of the shaft in the bearings, tighten (but don't over-tighten) all nuts on the bearings, supports and angles to Pawl connections. Carefully remove the shaft and you can be sure that your flywheels will be aligned and turn relatively easily when the crankshaft is made and in place later.

The main beam is relatively straight- forward and can be made from following the plan view. Each of the four beam arm segments are made from two each BI and BJ flat beam girders overlapped one hole. The spacing between the arm girders is maintained by M small double angles on the inner edge and by a pair of DP angle girders on the outer edge. The girders are bolted through the end middle holes at both the inner and outer connection points forming the parallelogram shown.

The correct spacing at the beam mid- point is obtained by overlapping two B girders to make the center bearing. The girders will make a member 7" between end holes. I used an 11-hole strip H centered on the girders and bolted to them at the correct attachment holes as the arm bearing pivot.

The end holes of this compound girder are bolted through the last middle holes of the arm girders. Two additional B girders are spaced six holes from the inner end of the upper arm girders and 10 holes from the end hole of the lower arms to complete the spacing support. The spacing supports are, of course, made on both sides of the beam arms.

The vertical arm supports are a little tricky, but the use of the AY Bull Ring and G 11-hole strips guarantee the correct spacing. I will give only some of the assembly highlights-by this time you have mastered the basics of working with the DV and BJ girders.

Four support arms, two left and two right, are made from two sections DV girders and one section Bl girder each. They are connected at the top by one AI Large Triangle which has one G seven-hole strip added as a bearing surface for the arm pivot.

The spacing between left and right arms is dictated by the AY Bull Ring and G strips mentioned above by fastening the G's to the fourth hole up from the lower end of the BJ girders. Additionally, a girder made of one A and one B girder is fastened to the top center hole of the Bull Ring and the lower hole of the AI Triangle.

A curved compound girder composed of three E girders overlapped such that the center E girder is exposed (behind) the two outer girders by two inches, is fastened to the second hole from the lower end of the second DV girder section. I used one compound curved girder on each side of the vertical arms. One further G strip is attached from the lower center hole in the Bull Ring to the center hole of the curved compound girder. An M double angle between the two compound curved girders at the middle adds rigidity.

The assembly will be quite stiff at this point. Two O Pawls (long side horizontal) are used as the anchoring means (to the base plates) for each pair of the support arms. The arms are attached to the base plates at the following locations: The right-hand arms are on the last hole of the cross member plates and 10 holes in from the front and rear base edge. The left-hand arms are 10 holes to the left of the right end of the cross base plates and also 10 holes in from the front and rear base edge.

An axle rod (CY), five inches long or thereabouts, is used as the main bearing for the beam between the upright arms. Use P37 collars for spacing of the axle, arms and beam. This does not give a very stable bearing in the front to rear axis, but that's the way it is without altering the design considerably from the plan book. It's strong enough for the model to function properly.

Cylinder and Guides

The cylinder is made from eight Boiler Plates BZ and capped with Bull Rings as per standard construction shown for No.10 set models. Guide rods for the piston are two axles 15" long, made from 5/32" drill rod. The rods are secured to the cylinder by placing them in BT pierced discs which are in turn bolted to the AZ Bull Ring Plate.

The guide rods are spaced 11 holes apart (based on " strip hole spacing) center to center. Decorative sides and back extending upward are made from standard curved and straight girders. The boiler is bolted to the base plates via two O Pawls which are spaced nine holes from the left end of the base. The boiler is centered from front to rear on the base.

The "Piston" is made from two L 21-hole Strip Brackets, attached to linkage which ends in formed strips that pivot in the center end holes of the Beam. The piston was so light that I found it necessary to add some weight in the form of strips fastened to the top of the piston with long bolts.

Another requirement for smooth operation was the counterbalance weights consisting of B girders added to the inside of the beam arms opposite the crankshaft. This was required because the crankshaft and connecting arm were much heavier than the piston end.

Crankshaft and Connecting Arm

The crankshaft will be extremely stiff and has no problem keeping the two flywheels turning in unison (as long as you followed the previous shaft alignment procedure). Each crankshaft half is composed of four H 21-hole strips joined in the following manner to make a box construction:

At the drive shaft end, BAX Bull Wheel Centers are fastened with _" bolts through their outer holes, through the H strips which are secured by nuts to the first BAX and then additional nuts placed on the bolts at " from the ends. Next, the second BAX and then H strips are placed on the bolts and nuts tightened over the H's. Cross members, F strips, are fastened at the 10th hole (midpoint) of the H strips with 7/8" bolts using the same technique as the previous construction.

Finally, at the end of the crankshaft, the inside cross support will be a BT pierced disc and outer cross member will be an additional F strip fastened as previously described.

Now the main flywheel axles can be inserted through the DV supports from the outer side, through the flywheel and into the inner support.

Place an EB collar on the inside and outside of the shaft and then place the crankshaft arms on the shafts, tightening the set screws (which for BAX is actually standard 8-32) so that the shaft is flush with the inside end of the inner BAX. Do not tighten the EB's until the connecting arm and pivot shaft are introduced to the scene.

The connecting arm is made as a square girder, that unique Gilbert invention that became the hallmark of Erector construction, often ridiculed, often cited as difficult to assemble. To the critics...I don't care about the critics. The square girder was light, strong, artistic, easy to assemble (following procedures) and could be made to any length required. To produce the square girder in Meccano, one girder wide (and I've done it), is really an exercise in tedious bolt placement. Anyway, back to the arm.

This arm is composed of both B and C girders with an overall hole count of seven holes. The front and rear sides are seven holes, the left and right sides are six holes. The upper holes (front and rear of the girder) extend one hole beyond the left and right sides, and are bolted to the lowermost holes on BT discs.

Carefully bend the B girders at the top so that the BT discs, with boss inward, clear the width of the Beam sides. A short axle secures the connecting arm to the beam, tightening the set screws in the BT's, allow just enough play for rotation.

The connecting arm is positioned so that the lower holes align with the crank arms. Two further BT's are placed at the lower end of the connecting arm, bosses out.

Now a seven-inch axle is passed through one crank arm (both BT and F), through one BT, through the lowest holes of the connecting arm, through one further BT and finally the second crank arm. Align the flywheels radially and tighten the set screws on the BT's of the crank arms so that the connecting arm is secured with little play remaining. At this time you can adjust and tighten the EB collars on both crankshafts, making sure that the crankshaft and assembly are centered in relation to the front and rear of the base, taking the boiler center line into consideration. The hard work is over.

You should be able to easily turn the flywheels while checking clearances as the Walking Beam makes an impressive arc. If you followed my hole-spacing criteria, the arm travel will clear all obstructions and be within one inch of maximum throw.

Motor and Drive

Do you have a working P56G motor that you would like to operate?

Most likely, if you are that fortunate, you should not run that motor, but keep it in good condition. I verify that it will operate the Walking Beam, although at a much faster than realistic speed.

The even more rare P57 motor could be used for photos. If, for some reason, you would like to operate the Walking Beam for an extended period, I recommend perhaps the common A49 motor and P7 pulley, which should give a realistic speed.

The correct mounting holes for the P56G motor are: Front mounting holes at the ninth hole from the front of the base, with left front mounting hole at the first hole of the base cross member. This will place the other mounting holes at the 12th hole from the base front. The brush caps of the motor should face forward. One DB motor pulley affixed to the motor shaft will do the job as the driver sheave.

I used red cotton string as the drive belt. Use small amounts of 3-in-One Oil on moving parts and you are ready to run.

Take lots of color photos and enjoy!

The model as built and described by Bob.

For a list of parts needed to build this model, send SASE to:

So. Cal. Meccano & Erector Club,
P.O.Box 7653,
Porter Ranch Station,
CA 91327-7653

Last Updated: October 1, 2000